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4.1.1 Probability (A-level only)

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Question 3

Two jars, J1 J_1\,J1​ and J2J_2J2​, contain blue, white, and black marbles. Jar J1 J_1\,J1​ contains 4 blue marbles, 3 white marbles, and 3 black marbles. Jar J2 J_2\,J2​ contains 2 blue marbles, 5 white marbles, and 1 black marble. Sam picks one marble at random from jar J1 J_1\,J1​ and places it into jar J2J_2J2​. Sam then picks one marble at random from jar J2J_2J2​.

a.

Draw a tree diagram to represent this information.

[2]
b.

Find the probability that Sam picks two marbles of the same colour.

[2]
c.

Given that both marbles are the same colour, find the probability they are both black.

[2]

4.1.1 Probability (A-level only) Questions

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